When a man describes himself as bisexual, we usually take this to mean that he has sexual relations with both men and women, and/or that he is attracted to both sexes. However, prior lab research has found that many men who self-identify as bi-sexual are not in fact sexually aroused – in a physical sense – by the opposite sex.

It’s important to remember that physical sexual arousal is only one reflection of a person’s sexual desires and identity, not the be all and end all. However, this past research suggests that, from a bio-psychological perspective, the label bisexual is used by a diverse group of men. A new study builds on this idea, and finds that a key distinguishing characteristic among bisexual men is their level of sexual curiosity.

Gerulf Rieger and his colleagues conducted two studies with hundreds of men, some of whom were recruited via university adverts, others via websites where men seek sexual partners. The first study used pupil dilation as an index of sexual arousal. The second study used increase in penile circumference as the measure of sexual arousal.

The men, who rated themselves on a sexual orientation sliding scale from strictly homosexual, to bisexual, to strictly heterosexual, watched video clips of attractive male or female models masturbating in the first study, or, in the second study, short videos of two men having sex, or two women having sex. In both studies, the participants also filled out a 10-item questionnaire about their sexual curiosity. Example items included “If I were invited to watch a porn movie, I would accept” and “Sex without love is appealing to me.”

On average, men who self-identified as bisexual showed the sexual arousal patterns you might expect, being less aroused than heterosexual men (but more aroused than homosexual men) by videos featuring women, and more aroused than heterosexual men by videos featuring men. This average data conceals the fact that some bisexual men were aroused by both sexes, while others were aroused only by men. The novel finding from this research is that these arousal patterns were correlated with sexual curiosity. Bisexual men on average reported more sexual curiosity than straight or gay men; moreover, among bisexual men only, greater sexual curiosity was linked with more arousal in response to videos featuring women. Bisexual men with low levels of sexual curiosity tended to be aroused only by other men.

Rieger and his colleagues speculate that shared genetic influences likely account for increased sexual curiosity and bisexual physiological arousal, thus explaining why these two characteristics correlate. They also propose that some bisexual men with elevated curiosity may “reattribute” their curiosity-related arousal to sexual stimuli depicting either sex, “thus increasing their sexual arousal and rewarding experiences associated with both men and women.” What about the bisexual men who are only aroused by men? Rieger’s team suggest that their identity may be in a transitional stage – perhaps they self-identify as bisexual on the basis of past experiences and relationships, or to conform to societal norms.

“The present findings are in line with the notion that a male bisexual identity can be found in a diverse range of men who differ in sexual attitudes and feelings,” the researchers said.

I wonder how much of this is due to heteronormativity — if there might not be a strong pressure for people with any capacity for opposite-sex attraction to ID as straight and be in straight relationships, thus skewing the sample of out bisexuals to people who are more on the same-sex side of things?

The pressure of heteronormativity is an interesting one. Anecdotally, I identified as a lesbian since coming out, but now that I have become more comfortable with my own sexually – over 12 years later – I actually see myself as more of bisexual. I think this was because of the pressure to identity as gay or straight and not “sit on the fence,” “have my cake and eat it,” “be greedy,” etc. etc.

There has definitely been a change in society, with people becoming more accepting of bisexuals, as well as my own maturity and not caring what other people think quite so much.

I don’t think it’s always a matter of either bisexual or gay or lesbian. It’s more of a matter of women having different size breasts and some growing them earlier than others. Women lots of times tease other women about about their breast sizes. Some women tease other women for being younger than them and being more busty than them.I know. I had that growing up in School about about growing tits when the rest of my classmates were still flat chested and being more busty than some of the older girls at School. I also had my in laws tease me for being more busty than them.Cathy